File download Extjs 2.3

Good afternoon in my timezone

I work as software developer in an enterprise, and recently i was exposed to ExtJs.
The application is already on production a few years ago and now i have to make evolution maintenance.
The problem is :
To download a file the application uses the following code:

The config object contains the name of the field inside the form, and this is working fine.
But sometimes a problem happens, when a user click on the button to download the file, and this handler runs, if one request that is originated through the load of a store is still loading , the load of the store abort immediatly and a pop up appears, this just happen if the the ajax request originated by the load of the store is still running.

store.load();

The ExtJs version is the 2.3. Is it a well known problem , that a load of a store can not be running side by side with a traditional form submit ?
The workaround that i am tyring to do is using the ExtJs form object , like this way :

I can see through the firebug that the POST is done like it should, and is working fine, but the server answer,in this case the file , do not open in the browser , the server sends the file and the browser simply do nothing.
This is because it is an Ajax request ?

Bottom line , how can i download a file through an Ext.form or at least through another workaround ?